'Art Tatum - 20th Century Piano Genius' is the most amazing solo piano recording I have ever heard.
Monk and Bill Evans are excellent recommendations. I would add Herbie Nichols and Bud Powell to the list, although most of the great recordings from the last two (not to mention the best Monk, IMO) are in a band context.
I love these kinds of threads. It's great to find new music to check out.